Conventionally, as a sealing material used for assembly of various kinds of electronic material modules, there has been proposed a resin composition comprising an ethylene-based copolymer as a base material and an organic peroxide as a crosslinking agent mixed with the ethylene-based copolymer (Patent Literature 1).
In addition, there has been proposed an adhesive sheet for a solar cell which is constituted of 100 parts by weight of an ethylene-based copolymer and 0.05 to 0.5 parts by weight of an organic peroxide, and comprises a multifunctional monomer having four or more acryloyl and/or methacryloyl groups in total (Patent Literature 2).
Further, there has been proposed a sealing film for a solar cell which comprises an ethylene-unsaturated ester copolymer, a crosslinking agent and a crosslinking aid, in which the crosslinking aid comprises a polyfunctional (meth)acrylate of a polyhydric alcohol and TAIC (Patent Literature 3).
Meanwhile, TAIC is known as a useful crosslinking aid upon obtaining a molded body by curing a cross-linkable polymer. In particular, when crosslinking an ethylene-based vinyl acetate copolymer with an organic peroxide, TAIC is essentially required as a crosslinking aid, and is capable of providing a sealing material for a solar cell which has high transparency, adhesive properties, heat resistance and flexibility. However, a polymer having a polar group such as an ethylene-vinyl acetate copolymer tends to be insufficient in insulation properties (volume resistivity value) even when cross-linked using TAIC. There is still room for improvement even when the polymer is used in combination with a polyfunctional (meth)acrylate of a polyhydric alcohol according to the above-proposed conventional art.